Printing unit for a high speed printer



Sept. 6, 1960 G. STUTZ ETAL PRINTING UNIT FOR A HIGH SPEED PRINTER 2 Sheets-Sheet 1 Filed Jan. 29, 1959 F lI/VENTORS. GERHART STUTZ OTTO BARTHRUFF ATTORNEY Sept. 6, 1960 c. STUTZ ETAL 2,951,439

PRINTING UNIT FOR A HIGH SPEED PRINTER 2 Sheets-Sheet 2 Filed Jan. 29, 1959 FIG.

PRINTING UNIT FOR A HIGH SPEED PRINTER Gerhart Stutz, Sindelfingen, and Otto Barthrutt, Stuttgart, Germany, as'signors to International Business Machines Corporation, New York, N.Y., a corporation of New York Filed Jan. 29, 1959, Ser. No. 789,831

Claims priority, application Germany Feb. 7, 1958 2 Claims. (Cl. 101-93) This invention relates to printing devices and more particularly to a printing unit for a high speed printer of the type commonly referred to as a stick printer.

in general, a stick printer comprises one or more cylinprinting speeds, the masses of the moved parts and particulariy of the print element must be kept as small as possible so that the accelerations occurringon the setup of those elements can be produced by forces obtainable from input mechanisms of reasonable size and capacity. However, the use of such print elements as strikers due: to their low mass entails a series of technical difficultieswhich could so far not be solved satisfactorily.

In additiomwhen hammers have been arranged behind the paper plane, there arose, besides the uncertainty in accurate paper alignment, loud printing noises and a. very high wear caused by hammer impact on the type surface.

Moreover, the large number of print elements must bealigned after each setup. Heretofore this has required. additional elements of apparatus operable in a manner which has resulted in some loss of time, thereby reducing: the speed of printing in an undesired manner.

Therefore, it is an object of this invention to provide an improved printing unit of the type having print elements settable by axial and rotational displacement which. has increased printing speed potential, reduced noise, reduction of type wear, more efiicient operation, a minimum number of parts, as well as better printing quality.

This and other objects to become apparent as the de scription proceeds are obtained in accordance with this; invention by providing a printing unit having a type carrying print element settable by axial displacement and rotation, hammer means located on the same side of the print medium as the print element and adapted to act di-- rectly on the print element for carrying it through the: printing operation in the direction toward the print medium plane. For avoiding damage to type characters from hammer impact, the invention further contemplates that the hammers will touch the print element only at areas free of type for transmitting the forces required forthe printing operation. It has proved to be of special. advantage to form the hammers so that the power transmission to the type carrier will be effected to areas lying symmetrically to the characters opposite to the characters to be printed. According to a further development of the invention, there are provided at the hammers and print element engaging surfaces which on an impact of a Patented Sept. 6, 1960 hammer on the type carrier eifects an alignment thereof in addition to effecting a movement of the print element in the direction toward the paper plane.

These arrangements serve to realize the number of advantages that could not be achieved with the arrangements known so far. Thus the entire structure of the printing unit becomes more comp-act and neater as the setup of the print element and the initiation of the printing operation are effected by elements arranged on a single side of the print medium. Due to the fact that the print medium, such as a paper web, is not suspended in. passing between the print elements and the hammers but may be moved over a printing platen, not only the noise caused by the printing operation is considerably reduced, but also the printing of additionally and separately insertable cards is made possible which is of considerable importance particularly in accounting machines. Particularly significant however is the increase in the printing speed eifected by the elimination of special aligning elements which heretofore became active between the setup of the type members and the hammer impact. According to the invention, the print elements are aligned laterally, axially and rotationally, thereby assuring a particularly uniform appearance of the printed text. The surface of the print element as provided for alignment may be either arranged in recesses between the individual types or produced by particular formation of the types themselves which are surrounded by a part of the hammer, preferably enclosing a conical space. Additional advantages and features will become apparent as the description proceeds, while the particular features of novelty are particularly pointed out in the appended claims.

Other objects of the invention will be pointed out in the following description and claims and illustratedin the accompanying drawings, which disclose, by way of examples, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. lis a partial sectional view of one embodiment of the printing unit of the invention incorporated in a printing device in which certain structural features have been omitted for clarity.

Pig. 2 shows an enlarged sectional view of a portion of Fig. lrepresenting the front part of the hammer.

Figs. 3 and 4 are sectional views perpendicular to the axis of the printing cylinder illustrating further embodiments of the hammer and type carrier construction of this invention.

Considering the invention in its various aspects and which Fig. 1 shows by way of example the printing device incorporating the printing unit of the present invention. For purposes of clarity, certain conventional structural features have been omitted.

The printing device structure comprises a platen 10, preferably formed of resiliently deformable materials, such as rubber, which may conveniently be part of a carriage mechanism including an ink ribbon 11, and means (not shown) for feeding a print medium, such as a paper web 12, between the ribbon and the platen. In accordance with conventional operation, platen 10 acts .as a backing member for web 12.

Located to the right of ink ribbon 1 1 is the printing unit of the present invention comprising a cylinder shaped print element 13 having a plurality of types 14 arranged axially and circumferentially over the peripheral surface thereof in the form of suitable columns and rows; The

print element 13 in the preferred embodiment takes the :form of a hollow cylinder and is part of an assembly comprisinga pair of plate members 15 having openings 49' Sustaining the print element 13 in position between the extremities of vertical shaft 17 is a connecting setup bell crank lever 18 pivotally supported on a horizontal shaft 19. Bell crank lever 18 is so arranged relative to print.

element 13 that oscillatory movement of the bell crank effects a linear (axial) displacement of print element 13 and associated assembly along the vertical shaft 17.

While any number of suitable arrangements may be provided for effecting the connection of bell crank lever and print element assembly, the preferred form calls for the upper plate 15 to rest on the end of one of the arms of bell crank lever 18 and to have a suitable opening for receiving a short extension 20 in a loose manner. The other arm of lever '18 is preferably connected to a coil spring 21 for overcoming the effect of gravity.

In its concentric arrangement relative to the vertical shaft 17, print element 13 is slideable therealong between predetermined limits corresponding to the upper and lowermost rows of type 14 thereon. In addition, print element 13 is keyed to shaft 17 so as to be rotatable thereby. Any suitable keying arrangement which permits slidable axial motion may be employed. However, the keying is preferably effected by shaping of the shaft and the print element. An example of such shaping may be seen by reference to Figs. 3 and 4 where the central opening of the print element is square and a corresponding cross-section is given to vertical shaft 17.

Rotational movement is transmitted to shaft -17 via gear elements 22 connected to the upper end thereof. In the preferred form, gear elements 22 are arranged concentrically about bushing 23 which in turn is fitted to the upper extremity of shaft 17, such as by nut 24 to serve as a means for maintaining shaft 17 rotationally suspended from the support block 25. A journal opening 26 in the support block 2 receives the upper end of shaft 17 in suitable rotatable connection.

- In addition to being axially displaceable and rotatable,

print element 13 is movable so as to strike against platen 10. For this reason, support block 25 is mounted so as to be pivotally movable about a horizontal axis transverse to the axis of the print element and the axis of shaft 17. For this purpose, support block '25 is provided with horizontal shaft extensions 27 which rest in suitable journals, not shown, in a support frame 28. Means for biasing print element 13 out of engagement with platen is provided by a flat spring 29 suitably anchored to a lower support frame member 36 and engaging the lower end of shaft 17. A groove 31 may be provided in the lower support frame 30 to receive and guide the lower end portion of shaft 17 to thereby limit somewhat the degree of lateral motion of shaft 17.

The vertical setup of print element 13 is obtained by causing print element to be moved axially to any one of several positions corresponding to the number of rows of type on its outer periphery. This is preferably accomplished by rotation of the bell crank lever 18 on shaft 19. Means for accomplishing such motion are well known to persons skilled in the art and a detailed discussion thereof is believed to be unnecessary. Similarly rotational settings of the type on print element 13 are accomplished by movement of shaft 17 through gear elements 22 to any one of the column positions of the type. Suitable means for accomplishing the desired settings are also well known to persons skilled in the art. The axial displacement and rotation may to reduce time for setup, be performed simultaneously in any manner known in the art.

In accordance with this invention, operating means is provided which directly engages the print element 13. In its preferred embodiment, the operating means takes the form of a lever shaped hammer 32 pivotally sup ported at one end to a horizontal shaft 33 and having a head portion 34 designed to contact print element 13 along the horizontal'print line 35. Means for operating the hammer in a counterclockwise direction to strike print element 13 suitably takes the form of a rotatable cam 36 designed to operate the'hammer 32 twice each complete revolution. A coil spring 37 connected to hammer 32 biases it in a clockwise direction toward engagement with cam 36.

In the preferred embodiment, cam is continuously operable and control of the printing operation is effected by controlling the degree of deflection of hammer 32 about its pivoted axis so as to control the contact of the hammer with the cam 36. The means for effecting control of the hammer 32 is preferably an electromagnet comprising a core 38, coil 39, and an armature 40 pivotally mounted on the core and biased by a suitable coil spring 41 in any well-known manner. The electromagnet is so positioned that the armature 40 extends into the path of movement of hammer 32. A pair of lugs 42 and 43 formed in the upper surface of armature 40 are adapted to abut the edge of the hammer to restrict its angular movement and thereby establish operative and inoperative positions. When coil 39 is not energized, the armature 40 is maintained away from the core 38 by the action of spring 41 so that lug 42 is in position to engage the hammer 32. Thus hammer 32 is maintained out of reach of cam 36 in an inoperative position. Energization of coil 39 causes the armature 40 to be deflected downwardly. Hammer 32 thereby is free to move past lug 42 under force supplied by spring 41 to ultimately become-engaged by lug 43. In the new angular position, hammer 32 is engageable by cam 36.

' the type which are embraced thereby.

. vidual types 14 are conically formed and are spaced from types in adjacent rows to provide free conically shaped areas 44 therebetween. The free areas 44 are engaged by cone shaped extensions 45 formed on the face of the head portion 34 of hammer 32. The extensions 45 are sufiiciently long to prevent direct contact with In addition to contacting print element 13 in free areas 44 to avoid wear of type portions 14, extensions 45, coacting with the conical surfaces of type 14, produce an aligning action of the type =14 relative to print line 35.

Fig. 3 illustrates a second embodiment of the printing unit according to the invention, whereby the print element is shaped in the free areas between the rows of [type to receive the correspondingly shaped hammer which is capable of aligning the print element in a rotational manner.

In accordance with this embodiment, the print element 13 may be an octagonal prism having surfaces in the free areas between type for coacting with the appropriate jaw-like extensions 46 of the head portion 34 of hammer 32. If the cross-section of the type 14 facing the hammer is too small for insuring an alignment mer 32 is provided with correspondingly shaped extensions 48, the side surfaces of which and corresponding 1 surfaces of recess 48 operating to align type 14 symmetrically positioned on the diametrically opposite side of the print element.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. In a printing device having a platen for backing a print medium, the combination comprising a cylindrical print element having a plurality of type disposed in columns and rows over the periphery thereof, said print element being movable so as to strike against said platen and being settable by axial and rotational movements, said columns and rows being spaced apart to provide free areas between each type therein, said free areas having impact receiving surfaces, said surfaces being arranged to efiect axial and rotational alignment of said print element upon movement to strike said platen, and hammer means operable to strike said print element to impel the same against said platen, said hammer means having a head portion adapted for striking said print element in the free areas thereof whereby said print element is impelled against said platen, said head portion having symmetrically arranged surfaces for cooperating with said impact receiving surfaces upon contact therewith to effect a simultaneous axial and rotational alignment of said print element whereby an aligned imprint of preset type is obtained.

2. In a printing device, the combination of claim 1 in which said impact receiving surfaces form funnel shaped recesses and said surfaces of said hammer head portion form an extension receivable within said funnel shaped recesses.

References Cited in the file of this patent UNITED STATES PATENTS 1,333,890 Wright Mar. 16, 1920 1,542,223 Dolph June 16, 1925 2,157,035 Torkelson May 2, 1939 2,623,455 Couffignal Dec. 30, 1952 2,834,289 Haberkorn May 13, 1958 

